An SCR has ___________ pn junctions

Consider the following statements: 1. In a silicon controlled rectifier (SCR), if the cathode gate is reverse-biased, then the SCR cannot fire at all. 2. The turn-on time of an SCR increases with temperature. 3. After an SCR is turned on, it can be made to turn off again by reverse biasing the gate. 4. Gate recovery time is the minimum time that the anode voltage must be maintained below holding voltage VH to turn off the SCR. Which of these statements are correct?

A

1, 2, 3 and 4

B

1 and 2 only

C

2 and 4 only

D

3 and 4 only

A National Highway road network has parallel and perpendicular roads running north-south or east-west only. Junctions/Intersections on this road network are marked as R1, R2, R3, R4... All roads are at exactly half a kilometer distance from each other. The following is known about junctions R1, R2, R3, R4, R8, and R24. “R1’ is east of ‘R2’ and west of ‘R3’; ‘R8’ is southwest of ‘R3’ and southwest of R2. ‘R2’ is southeast of ‘R24’. Which junctions are the farthest south and the farthest east?

A

R1, R2

B

R8, R3

C

R3, R8

D

R2, R8

A 220 1-ϕ, 220 Ω resistor is connected in series with the gate of an SCR as shown in the given figure. The gate current required to fire the SCR is 7 mA. what is the input voltage (Vin) required to fire the SCR?

A

2.60 V

B

2.24 V

C

4.12 V

D

1.6 V

A voltage source Vs = Vm sinωt is connected in series with a resistance R and an SCR. At some firing angle delay of α a positive gate pulse is applied to the SCR which turns on the SCR. Considering ideal conditions, at the instant α the voltage at the resistor terminals Vo

A

falls to zero

B

falls to –Vm sin α

C

rises to Vm sin α

D

rises to Vm sin ωt

A road network has parallel roads, which are equidistant from each other and running North-South or East-West only. The road junctions A, B, C, H and X are such that A is East of B and West of C. H is South-West of C and South-East of B. B is South-East of X. Which of the junctions are the farthest South and the farthest East?

A

H, B

B

H, C

C

C, H

D

B, H

A train travels at a speed of 66 km/h and halts at five junctions for a certain time. It covers a distance of 1485 km in one day. For how long (in minutes) does the train stop at each junction, if it halts for the same period of time at all the junctions?

A

20

B

15

C

18

D

12

Tight junctions are made up of single junctions in our body.

A

True

B

False

When cathode is positive with respect to anode in an SCR, the number of blocked p-n junctions is

A

1

B

2

C

3

D

4

How many layers and junctions does an SCR have?

A

Four layers and three junctions

B

Three layers and four junctions

C

Three layers and three junctions

D

Four layers and four junctions

From the two transistor (T1 & T2) analogy of SCR, the total anode current of SCR is ___________ in the equivalent circuit.

A

the sum of both the base currents

B

the sum of both the collector current

C

the sum of base current of T1 & collector current of T2

D

the sum of base current of T2 & collector current of T1

An SCR has ___________ pn junctions

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